Effects of Fecal Microbiota Transplantation With Oral Capsules in Obese Patients

Comparison of the use of a spiral nasojejunal tube and transendoscopic enteral tubing in washed microbiota transplantation via the mid-gut route

Background

Methods for washed microbiota transplantation (WMT) through the mid-gut include transendoscopic enteral tubing (TET) and manual spiral nasojejunal tube (SNT) placement have not been studied.

Methods

This prospective interventional study was performed at a single centre. Patients were divided into the SNT and mid-gut TET groups based on their conditions and wishes. In the SNT group, an SNT was passively inserted into the stomach, and abdominal X-rays were taken within 24 h to confirm tube placement in the small intestine. In the mid-gut TET group, mid-gut TET was placed in the small intestine for gastroscopy. Data on the clinical efficacy of WMT, intubation time, cost, overall comfort score, adverse reactions, etc., were collected from the two groups.

Results

Sixty-three patients were included in the study (SNT group (n = 40) and mid-gut TET group (n = 23)). The clinical efficacy of WMT in the SNT and mid-gut TET groups was 90 % and 95.7 %, respectively (P = 0.644). Compared with the mid-gut TET group, the SNT group showed a shorter operation time (120 s vs. 258 s, P = 0.001) and a lower average cost (641.7 yuan vs. 1702.1 yuan, P = 0.001). There was no significant difference in the overall comfort score or the incidence of common discomfort symptoms between the two groups.

Conclusion

The different implantation methods have different advantages; compared with mid-gut TET placement, manual SNT placement provides some benefits.

Prostate and gut: Any relationship? A narrative review on the available evidence and putative mechanisms

BACKGROUND

Gut microbiome is a community of microorganisms that lives in the human intestine and exerts various functions on the host, including metabolic, immunoregulatory, and control over cell proliferation. Gut microbiome alterations have been associated with various pathological conditions, such as diabetes mellitus, obesity, and cardiovascular diseases. Gut-prostate axis is explained by the association between gut microbiome quantitative and functional alterations along with increased intestinal epithelial permeability with prostatediseases. However, the pathophysiological mechanisms and clinical importance of this association are not completely clarified yet.

METHODS

We conducted a narrative review of the most relevant articles in the Medline (US National Library of Medicine, Bethesda, MD, USA), Scopus (Elsevier, Amsterdam, The Netherlands) and Web of Science Core Collection (Thomson Reuters, Toronto, ON, Canada) databases. No chronological restrictions were applied, and the most related papers published until December 2023 were included.

RESULTS

Gut microbiota (GM) and its metabolites are capable of modifying host androgen level, as well as prostate cancer (PCa) therapy response. Moreover, patients with inflammatory bowel disease have higher rates of prostatitis-like symptoms and a potential risk of developing PCa.

CONCLUSIONS

There is evidence that interventions on the GM and its metabolites have a high potential to serve as diagnostic and therapeutic tools for prostate diseases, including PCa.

Microbial Translocation and Gut Damage Are Associated With an Elevated Fast Score in Women Living With and Without HIV

Background

Steatohepatitis is common in persons living with HIV and may be associated with gut microbial translocation (MT). However, few studies have evaluated the gut-liver axis in persons living with HIV. In the Women's Interagency HIV Study, we examined the associations of HIV and circulating biomarkers linked to MT and gut damage using the FibroScan-aspartate aminotransferase (FAST) score, a noninvasive surrogate for steatohepatitis with advanced fibrosis.

Methods

Among 883 women with HIV and 354 without HIV, we used multivariable regression to examine the associations of HIV and serum biomarkers linked to MT and gut damage (kynurenine and tryptophan ratio, intestinal fatty acid-binding protein, soluble CD14, and soluble CD163) with a log-transformed FAST score after adjusting for key covariates. We used a path analysis and mediation models to determine the mediating effect of each biomarker on the association of HIV with FAST.

Results

HIV infection was associated with a 49% higher FAST score. MT biomarker levels were higher in women with HIV than women without HIV (P < .001 for each). MT biomarkers mediated 13% to 32% of the association of HIV and FAST score.

Conclusions

Biomarkers linked to MT and gut damage are associated with a higher FAST score and mediate the association of HIV with a higher FAST score. Our findings suggest that MT may be an important mechanism by which HIV increases the risk of steatohepatitis with advanced fibrosis.

The use of faecal microbiota transplant as treatment for recurrent or refractory Clostridioides difficile infection and other potential indications: second edition of joint British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS) guidelines

The first British Society of Gastroenterology (BSG) and Healthcare Infection Society (HIS)-endorsed faecal microbiota transplant (FMT) guidelines were published in 2018. Over the past 5 years, there has been considerable growth in the evidence base (including publication of outcomes from large national FMT registries), necessitating an updated critical review of the literature and a second edition of the BSG/HIS FMT guidelines. These have been produced in accordance with National Institute for Health and Care Excellence-accredited methodology, thus have particular relevance for UK-based clinicians, but are intended to be of pertinence internationally. This second edition of the guidelines have been divided into recommendations, good practice points and recommendations against certain practices. With respect to FMT for Clostridioides difficile infection (CDI), key focus areas centred around timing of administration, increasing clinical experience of encapsulated FMT preparations and optimising donor screening. The latter topic is of particular relevance given the COVID-19 pandemic, and cases of patient morbidity and mortality resulting from FMT-related pathogen transmission. The guidelines also considered emergent literature on the use of FMT in non-CDI settings (including both gastrointestinal and non-gastrointestinal indications), reviewing relevant randomised controlled trials. Recommendations are provided regarding special areas (including compassionate FMT use), and considerations regarding the evolving landscape of FMT and microbiome therapeutics.

Effects of fecal microbiota transfer on blood pressure in animal models: A systematic review and meta-analysis

BACKGROUND

Numerous recent studies have found a strong correlation between intestinal flora and the occurrence of hypertension. However, it remains unclear whether fecal microbiota transfer might affect the blood pressure of the host. This study aimed to quantify both associations.

METHODS

An electronic search was conducted in PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang database, Weipu, Embase, and SinoMed to retrieve relevant studies. The final search was completed on August 22, 2022. Two authors independently applied the inclusion criteria, extracted data, and assessed the risk of bias assessment. All data were analyzed using RevMan 5.4.

RESULTS

A total of 5 articles were selected for final inclusion. All studies were assessed as having a high risk of bias according to the SYRCLE risk of bias tool. The meta-analysis results showed that transplantation of fecal bacteria from the hypertensive model can significantly improve the host's systolic pressure (MD = 18.37, 95%CI: 9.74~26.99, P<0.001), and diastolic pressure (MD = 17.65, 95%CI: 12.37~22.93, P<0.001). Subgroup analyses revealed that the increase in systolic pressure in the hypertension model subgroup (MD = 29.56, 95%CI = 23.55-35.58, P<0.001) was more pronounced than that in the normotensive model subgroup (MD = 12.48, 95%CI = 3.51-21.45, P<0.001).

CONCLUSION

This meta-analysis suggests a relationship between gut microbiota dysbiosis and increased blood pressure, where transplantation of fecal bacteria from the hypertensive model can cause a significant increase in systolic pressure and diastolic pressure in animal models.

The structural characterization of a novel Chinese yam polysaccharide and its hypolipidemic activity in HFD-induced obese C57BL/6J mice

Obesity was considered as a rapidly growing chronic disease that influences human health worldwide. In this study, we investigated the primary structure characteristics of Chinese yam polysaccharide (CYP) and its role in regulating lipid metabolism in a high-fat diet (HFD)-fed obese mice. The molecular weight of CYP was determined to be 3.16 × 103 kDa. Periodic acid oxidation & smith degradation and nuclear magnetic resonance results suggested that CYP consists of 1 → 2, 1 → 2, 6, 1 → 4, 1 → 4, 6, 1→, or 1 → 6 glycoside bonds. The in vivo experiment results suggested that the biochemical indices, tissue sections, and protein regulation associated with lipid metabolism were changed after administering CYP in obese mice. In addition, the abundances of short-chain fatty acid (SCFA)-producing bacteria Lachnospiraceae, Lachnospiraceae_NK4A136_group, and Ruminococcaceae_UCG-014 were increased, and the abundances of bacteria Desulfovibrionaceae and Ruminococcus and metabolites of arginine, propionylcarnitine, and alloisoleucine were decreased after CYP intervention in obese mice. Spearman's correlation analysis of intestinal flora, metabolites, and lipid metabolism parameters showed that CYP may affect lipid metabolism in obese mice by regulating the intestinal environment. Therefore, CYP may be used as a promising nutritional intervention agent for lipid metabolism.

Standards for fecal microbiota transplant: Tools and therapeutic advances

Fecal microbiota transplantation (FMT) has been demonstrated to be efficacious in preventing recurrent Clostridioides difficile (C. difficile) infections, and is being investigated for treatment of several other diseases including inflammatory bowel disease, cancer, obesity, liver disease, and diabetes. To speed up the translation of FMT into clinical practice as a safe and standardized therapeutic intervention, additional evidence-based technical and regulatory guidance is needed. To this end in May of 2022, the International Alliance for Biological Standardization (IABS) and the BIOASTER Microbiology Technology Institute hosted a second webinar to discuss key issues still impeding the advancement and standardization of FMT. The goal of this two-day webinar was to provide a forum for scientific experts to share and discuss data and key challenges with one another. Discussion included a focus on the evaluation of safety, efficacy, clinical trial design, reproducibility and accuracy in obtained microbiome measurements and data reporting, and the potential for standardization across these areas. It also focused on increasing the application potential and visibility of FMT beyond treating C. difficile infections.

The effects of ambient temperature and feeding regimens on cecum bacteria composition and circadian rhythm in growing rabbits

Seasonal environmental shifts and improper eating habits are the important causes of diarrhea in children and growing animals. Whether adjusting feeding time at varying temperatures can modify cecal bacterial structure and improve diarrhea remains unknown. Three batches growing rabbits with two groups per batch were raised under different feeding regimens (fed at daytime vs. nighttime) in spring, summer and winter separately, and contents were collected at six time points in 1 day and used 16S rRNA sequencing to investigate the effects of feeding regimens and season on the composition and circadian rhythms of cecum bacteria. Randomized forest regression screened 12 genera that were significantly associated with seasonal ambient temperature changes. Nighttime feeding reduced the abundance of the conditionally pathogenic bacteria Desulfovibrio and Alistipes in summer and Campylobacter in winter. And also increases the circadian rhythmic Amplicon Sequence Variants in the cecum, enhancing the rhythm of bacterial metabolic activity. This rhythmic metabolic profile of cecum bacteria may be conducive to the digestion and absorption of nutrients in the host cecum. In addition, this study has identified 9 genera that were affected by the combination of seasons and feeding time. In general, we found that seasons and feeding time and their combinations affect cecum composition and circadian rhythms, and that daytime feeding during summer and winter disrupts the balance of cecum bacteria of growing rabbits, which may adversely affect cecum health and induce diarrhea risk.

Exploring the Dynamic Relationship between the Gut Microbiome and Body Composition across the Human Lifespan: A Systematic Review

This systematic review aimed to identify different gut microbiome profiles across the human lifespan and to correlate such profiles with the body composition. PubMed, Scopus, and Cochrane were searched from inception to March 2022. Sixty studies were included in this systematic review. Overall, the gut microbiome composition in overweight participants exhibited decreased α-diversity, decreased levels of the phylum Bacteroidetes and its taxa, and increased levels of the phylum Firmicutes, its taxa, and the Firmicutes/Bacteroidetes ratio, in comparison to normal-weight participants. Other body composition parameters showed similar correlations. Fat mass and waist circumference were found to correlate positively with the Firmicutes taxa and negatively with the Bacteroidetes taxa. In contrast, lean body mass and muscle mass demonstrated a positive correlation with the Bacteroidetes taxa. Notably, these correlations were more pronounced in athletes than in obese and normal-weight individuals. The composition of the gut microbiome is evidently different in overweight individuals or athletes of all age groups, with the former tending towards decreased Bacteroidetes taxa and increased Firmicutes taxa, while a reversed relationship is observed concerning athletes. Further studies are needed to explore the dynamic relationship between energy intake, body composition, and the gut microbiome across the human lifespan.

Fecal Microbiota Transplantation: A Prospective Treatment for Type 2 Diabetes Mellitus

Purpose of Review

The aim of this review is to summarize the role of gastrointestinal microbiome (GM) in the development of type 2 diabetes mellitus (T2DM). Besides, we discuss the feasibility of applying FMT in the treatment of T2DM and propose a series of processes to refine the use of FMT in the treatment of T2DM.

Recent Findings

T2DM is a metabolic disease which is connected with the GM. According to many researches, GM can produce a variety of metabolites such as bile acid, short chain fatty acids, lipopolysaccharides and trimethylamine oxide which play an important role in metabolism. FMT is a method to regulate GM and has been observed to be effective in the treatment of metabolic diseases such as T2DM in some mouse models and people. However, there is still a lack of direct evidence for the use of FMT in the treatment of T2DM, and the process of FMT is not standardized.

Summary

Dysregulation of GM is closely related to the development of T2DM. Promoting the conversion of GM in T2DM patients to normal population through FMT can reduce insulin resistance and lower their blood glucose level, which is an optional treatment for T2DM patients in the future. At present, the feasibility and limitations of applying FMT to the treatment of T2DM need to be further studied.

The Effect of Fecal Microbiota Transplantation on Cardiometabolic Risk Factors: A Systematic Review and Meta-Analysis

PURPOSE

Cardiometabolic disease (CMD) is increasing along with its predisposing factors and adverse consequences. As gut microbiota dysbiosis is established in these patients, fecal microbiota transplantation (FMT), which alters the bacterial composition of the intestine, supposedly can help improve cardiometabolic disturbances. We conducted a systematic review and meta-analysis evaluating the impact of FMT on the cardiometabolic parameters and gut microbiota composition of patients experiencing at least one cardiometabolic issue.

METHODS

Eligible studies were searched through the PubMed, Web of Science, and Scopus databases until December 2022. The initial search results underwent duplication removal and screening until each included study was scanned for intended data. The Cochrane risk of bias tool was used to evaluate the methodologic accuracy of studies and the random effects model was used for conducting the meta-analysis.

FINDINGS

Eighteen of the original 2414 articles from the literature search were entered into the systematic review; of these, 11 were included in the meta-analysis. Insulin showed a significant decrease by 24.7 pmol/L (weighted mean difference [WMD], -24.77; 95% CI, -48.704 to -0.848) after short-term follow-up, and HDL increased by 0.1 mmol/l(WMD, 0.106; 95% CI, 0.027 to 0.184) and 0.12 mmol/l(WMD, 0.120; 95% CI, 0.003 to 0.237) in those using a capsule deliver mode and in short-term follow-up, respectively. No significant changes were seen in other lipid profiles, blood glucose, insulin resistance, or anthropometric indices. In addition, multiple studies reported gut microbiota alterations after the intervention, including an increase in butyrate-producing species.

IMPLICATIONS

Although some articles reported the beneficial effects of FMT on metabolic parameters, we failed to find a clinically significant alteration. Also, information regarding proper donors and the best method to induce FMT have not yet been sufficiently investigated, which should be considered along with means to prevent potential damages. PROSPERO identifier: CRD42022380705.

Human gut microbiome: Therapeutic opportunities for metabolic syndrome-Hype or hope?

Shifts in gut microbiome composition and metabolic disorders are associated with one another. Clinical studies and experimental data suggest a causal relationship, making the gut microbiome an attractive therapeutic goal. Diet, intake of probiotics or prebiotics and faecal microbiome transplantation (FMT) are methods to alter a person's microbiome composition. Although FMT may allow establishing a proof of concept to use microbiome modulation to treat metabolic disorders, studies show mixed results regarding the effects on metabolic parameters as well as on the composition of the microbiome. This review summarizes the current knowledge on diet, probiotics, prebiotics and FMT to treat metabolic diseases, focusing on studies that also report alterations in microbiome composition. Furthermore, clinical trial results on the effects of common drugs used to treat metabolic diseases are synopsized to highlight the bidirectional relationship between the microbiome and metabolic diseases. In conclusion, there is clear evidence that microbiome modulation has the potential to influence metabolic diseases; however, it is not possible to distinguish which intervention is the most successful. In addition, a clear commitment from all stakeholders is necessary to move forward in the direction of developing targeted interventions for microbiome modulation.

Dietary resistant starch supplementation increases gut luminal deoxycholic acid abundance in mice

Bile acids (BA) are among the most abundant metabolites produced by the gut microbiome. Primary BAs produced in the liver are converted by gut bacterial 7-α-dehydroxylation into secondary BAs, which can differentially regulate host health via signaling based on their varying affinity for BA receptors. Despite the importance of secondary BAs in host health, the regulation of 7-α-dehydroxylation and the role of diet in modulating this process is incompletely defined. Understanding this process could lead to dietary guidelines that beneficially shift BA metabolism. Dietary fiber regulates gut microbial composition and metabolite production. We tested the hypothesis that feeding mice a diet rich in a fermentable dietary fiber, resistant starch (RS), would alter gut bacterial BA metabolism. Male and female wild-type mice were fed a diet supplemented with RS or an isocaloric control diet (IC). Metabolic parameters were similar between groups. RS supplementation increased gut luminal deoxycholic acid (DCA) abundance. However, gut luminal cholic acid (CA) abundance, the substrate for 7-α-dehydroxylation in DCA production, was unaltered by RS. Further, RS supplementation did not change the mRNA expression of hepatic BA producing enzymes or ileal BA transporters. Metagenomic assessment of gut bacterial composition revealed no change in the relative abundance of bacteria known to perform 7-α-dehydroxylation. P. ginsenosidimutans and P. multiformis were positively correlated with gut luminal DCA abundance and increased in response to RS supplementation. These data demonstrate that RS supplementation enriches gut luminal DCA abundance without increasing the relative abundance of bacteria known to perform 7-α-dehydroxylation.

Review on chronic metabolic diseases surrounding bile acids and gut microbiota: What we have explored so far

Bile acid, the final product of cholesterol breakdown, functions as a complex regulator and signaling factor in human metabolism. Chronic metabolic diseases pose significant medical challenges. Growing research underscores bile acids' capacity to enhance metabolism via diverse pathways, regulating disorders and offering treatment potential. Numerous bile-acid-triggered pathways have become treatment targets. This review outlines bile acid synthesis, its role as a signal in chronic metabolic diseases, and highlights its interaction with gut microbiota in different metabolic conditions. Exploring host-bacteria-bile acid links emerges as a valuable future research direction with clinical implications.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Gut liver brain axis in diseases: the implications for therapeutic interventions

Gut-liver-brain axis is a three-way highway of information interaction system among the gastrointestinal tract, liver, and nervous systems. In the past few decades, breakthrough progress has been made in the gut liver brain axis, mainly through understanding its formation mechanism and increasing treatment strategies. In this review, we discuss various complex networks including barrier permeability, gut hormones, gut microbial metabolites, vagus nerve, neurotransmitters, immunity, brain toxic metabolites, β-amyloid (Aβ) metabolism, and epigenetic regulation in the gut-liver-brain axis. Some therapies containing antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), polyphenols, low FODMAP diet and nanotechnology application regulate the gut liver brain axis. Besides, some special treatments targeting gut-liver axis include farnesoid X receptor (FXR) agonists, takeda G protein-coupled receptor 5 (TGR5) agonists, glucagon-like peptide-1 (GLP-1) receptor antagonists and fibroblast growth factor 19 (FGF19) analogs. Targeting gut-brain axis embraces cognitive behavioral therapy (CBT), antidepressants and tryptophan metabolism-related therapies. Targeting liver-brain axis contains epigenetic regulation and Aβ metabolism-related therapies. In the future, a better understanding of gut-liver-brain axis interactions will promote the development of novel preventative strategies and the discovery of precise therapeutic targets in multiple diseases.

Successful weight regain attenuation by autologous fecal microbiota transplantation is associated with non-core gut microbiota changes during weight loss; randomized controlled trial

We previously reported that autologous-fecal-microbiota-transplantation (aFMT), following 6 m of lifestyle intervention, attenuated subsequent weight regain and insulin rebound for participants consuming a high-polyphenol green-Mediterranean diet. Here, we explored whether specific changes in the core (abundant) vs. non-core (low-abundance) gut microbiome taxa fractions during the weight-loss phase (0-6 m) were differentially associated with weight maintenance following aFMT. Eighty-two abdominally obese/dyslipidemic participants (age = 52 years; 6 m weightloss = -8.3 kg) who provided fecal samples (0 m, 6 m) were included. Frozen 6 m's fecal samples were processed into 1 g, opaque and odorless aFMT capsules. Participants were randomly assigned to receive 100 capsules containing their own fecal microbiota or placebo over 8 m-14 m in ten administrations (adherence rate > 90%). Gut microbiome composition was evaluated using shotgun metagenomic sequencing. Non-core taxa were defined as ≤ 66% prevalence across participants. Overall, 450 species were analyzed. At baseline, 13.3% were classified as core, and Firmicutes presented the highest core proportion by phylum. During 6 m weight-loss phase, abundance of non-core species changed more than core species (P < .0001). Subject-specific changes in core and non-core taxa fractions were strongly correlated (Jaccard Index; r = 0.54; P < .001). Following aFMT treatment, only participants with a low 6 m change in core taxa, and a high change in non-core taxa, avoided 8-14 m weight regain (aFMT = -0.58 ± 2.4 kg, corresponding placebo group = 3.18 ± 3.5 kg; P = .02). In a linear regression model, low core/high non-core 6 m change was the only combination that was significantly associated with attenuated 8-14 m weight regain (P = .038; P = .002 for taxa patterns/treatment intervention interaction). High change in non-core, low-abundance taxa during weight-loss might mediate aFMT treatment success for weight loss maintenance.ClinicalTrials.gov: NCT03020186.

New Awareness of the Interplay Between the Gut Microbiota and Circadian Rhythms

Circadian rhythms influence various aspects of the biology and physiology of the host, such as food intake and sleep/wake cycles. In recent years, an increasing amount of genetic and epidemiological data has shown that the light/dark cycle is the main cue that regulates circadian rhythms. Other factors, including sleep/wake cycles and food intake, have necessary effects on the composition and rhythms of the gut microbiota. Interestingly, the gut microbiota can affect the circadian rhythm of hosts in turn through contact-dependent and contact-independent mechanisms. Furthermore, the gut microbiota has been shown to regulate the sleep/wake cycles through gut-brain-microbiota interaction. In addition to diabetes, the gut microbiota can also intervene in the progression of neuro- degenerative diseases through the gut-brain-microbiota interaction, and also in other diseases such as hypertension and rheumatoid arthritis, where it is thought to have a spare therapeutic potential. Even though fecal microbiota transplantation has good potential for treating many diseases, the risk of spreading intestinal pathogens should not be ignored.

Danger-associated metabolites trigger metaflammation: A crowbar in cardiometabolic diseases

Cardiometabolic diseases (CMDs) are characterized by a series of metabolic disorders and chronic low-grade inflammation. CMDs contribute to a high burden of mortality and morbidity worldwide. Host-microbial metabolic regulation that triggers metaflammation is an emerging field of study that promotes a new perspective for perceiving cardiovascular risks. The term metaflammation denotes the entire cascade of immune responses activated by a new class of metabolites known as "danger-associated metabolites" (DAMs). It is being proposed by the present review for the first time. We summarize current studies covering bench to bedside aspects of DAMs to better understand CMDs in the context of DAMs. We have focused on the involvement of DAMs in the pathophysiological development of CMDs, including the disruption of immune homeostasis and chronic inflammation-triggered damage leading to CMD-related adverse events, as well as emerging therapeutic approaches for targeting DAM metabolism in CMDs.

Gut microbiota-bile acid crosstalk regulates murine lipid metabolism via the intestinal FXR-FGF19 axis in diet-induced humanized dyslipidemia

BACKGROUND

Diet-induced dyslipidemia is linked to the gut microbiota, but the causality of microbiota-host interaction affecting lipid metabolism remains controversial. Here, the humanized dyslipidemia mice model was successfully built by using fecal microbiota transplantation from dyslipidemic donors (FMT-dd) to study the causal role of gut microbiota in diet-induced dyslipidemia.

RESULTS

We demonstrated that FMT-dd reshaped the gut microbiota of mice by increasing Faecalibaculum and Ruminococcaceae UCG-010, which then elevated serum cholicacid (CA), chenodeoxycholic acid (CDCA), and deoxycholic acid (DCA), reduced bile acid synthesis and increased cholesterol accumulation via the hepatic farnesoid X receptor-small heterodimer partner (FXR-SHP) axis. Nevertheless, high-fat diet led to decreased Muribaculum in the humanized dyslipidemia mice induced by FMT-dd, which resulted in reduced intestinal hyodeoxycholic acid (HDCA), raised bile acid synthesis and increased lipid absorption via the intestinal farnesoid X receptor-fibroblast growth factor 19 (FXR-FGF19) axis.

CONCLUSIONS

Our studies implicated that intestinal FXR is responsible for the regulation of lipid metabolism in diet-induced dyslipidemia mediated by gut microbiota-bile acid crosstalk. Video Abstract.

Evidence for the contribution of the gut microbiome to obesity and its reversal

Obesity has become a worldwide pandemic affecting more than 650 million people and is associated with a high burden of morbidity. Alongside traditional risk factors for obesity, the gut microbiome has been identified as a potential factor in weight regulation. Although rodent studies suggest a link between the gut microbiome and body weight, human evidence for causality remains scarce. In this Review, we postulate that existing evidence remains to establish a contribution of the gut microbiome to the development of obesity in humans but that modified probiotic strains and supraphysiological dosages of microbial metabolites may be beneficial in combatting obesity.

Role of anthraquinones in combating insulin resistance

Insulin resistance presents a formidable public health challenge that is intricately linked to the onset and progression of various chronic ailments, including diabetes, cardiovascular disease, hypertension, metabolic syndrome, nonalcoholic fatty liver disease, and cancer. Effectively addressing insulin resistance is paramount in preventing and managing these metabolic disorders. Natural herbal remedies show promise in combating insulin resistance, with anthraquinone extracts garnering attention for their role in enhancing insulin sensitivity and treating diabetes. Anthraquinones are believed to ameliorate insulin resistance through diverse pathways, encompassing activation of the AMP-activated protein kinase (AMPK) signaling pathway, restoration of insulin signal transduction, attenuation of inflammatory pathways, and modulation of gut microbiota. This comprehensive review aims to consolidate the potential anthraquinone compounds that exert beneficial effects on insulin resistance, elucidating the underlying mechanisms responsible for their therapeutic impact. The evidence discussed in this review points toward the potential utilization of anthraquinones as a promising therapeutic strategy to combat insulin resistance and its associated metabolic diseases.

Unraveling the Interplay: Exploring the Links Between Gut Microbiota, Obesity, and Psychological Outcomes

This narrative review delves into the complex and intricate mechanisms of the gut-brain axis. Gut microbiota has gained immense importance in the treatment of various diseases. The therapeutic potential of gut-microbial modulation is slowly coming to light. With good preclinical evidence, some human studies shed light on the translation potential of gut-microbial modulation. The concept of gut-microbial modulation has been studied for over a few decades. The relationship between gut microbiota and various homeostatic mechanisms is fascinating. Over the years, we have started understanding the immense role of gut microbiota in various homeostatic mechanisms. There are a good number of clinical studies that have shown the therapeutic potential of gut-microbial modulation in obesity and psychological diseases, especially depression and anxiety. The gut-microbial modulation can be achieved by dietary factors or supplementation. In this review, we explore the mechanisms by which prebiotics, probiotics, and synbiotics alter the gut-brain axis. The review limits its discussion to the most recent clinical studies that have shown promise as therapeutic strategies.

Gut microbiota and stroke: New avenues to improve prevention and outcome

Despite major recent therapeutic advances, stroke remains a leading cause of disability and death. Consequently, new therapeutic targets need to be found to improve stroke outcome. The deleterious role of gut microbiota alteration (often mentioned as "dysbiosis") on cardiovascular diseases, including stroke and its risk factors, has been increasingly recognized. Gut microbiota metabolites, such as trimethylamine-N-oxide, short chain fatty acids and tryptophan, play a key role. Evidence of a link between alteration of the gut microbiota and cardiovascular risk factors exists, with a possible causality link supported by several preclinical studies. Gut microbiota alteration also seems to be implicated at the acute phase of stroke, with observational studies showing more non-neurological complications, higher infarct size and worse clinical outcome in stroke patients with altered microbiota. Microbiota targeted strategies have been developed, including prebiotics/probiotics, fecal microbiota transplantation, short chain fatty acid and trimethylamine-N-oxide inhibitors. Research teams have been using different time windows and end-points for their studies, with various results. Considering the available evidence, it is believed that studies focusing on microbiota-targeted strategies in association with conventional stroke care should be conducted. Such strategies should be considered according to three therapeutic time windows: first, at the pre-stroke (primary prevention) or post-stroke (secondary prevention) phases, to enhance the control of cardiovascular risk factors; secondly, at the acute phase of stroke, to limit the infarct size and the systemic complications and enhance the overall clinical outcome; thirdly, at the subacute phase of stroke, to prevent stroke recurrence and promote neurological recovery.

Questioning the foundations of the gut microbiota and obesity

The role of the gut microbiota in determining body fatness has been a prominent area of research and has received significant public attention. Based largely on animal studies, recent attempts to translate these findings into interventions in humans have not been successful. This review will outline the key mouse research that initiated this area of study, examine whether those results warranted the initial enthusiasm and progress into human studies, and examine whether later follow-up research supported earlier conclusions. It will look at whether the absence of a gut microbiota protects germ-free mice from obesity, whether microbiota can transfer obesity into germ-free mice, the evidence for the role of immune system activation as a causal mechanism linking the gut microbiota to body weight, and consider the evidence for effects of individual bacterial species. Finally, it will examine the outcomes of randomized controlled trials of microbiota transfer in human participants that have not shown effects on body weight. With a more critical reading, early studies did not show as large an effect as first appeared and later research, including human trials, has failed to support a role of the gut microbiota in shaping body weight. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

Blueberry and Blackberry Anthocyanins Ameliorate Metabolic Syndrome by Modulating Gut Microbiota and Short-Chain Fatty Acids Metabolism in High-Fat Diet-Fed C57BL/6J Mice

In this study, blueberry (Vaccinium ssp.) anthocyanins (VA) and blackberry (Rubus L.) anthocyanins (RA) were used to investigate the effects on metabolic syndrome (MetS) and the potential mechanisms. Importantly, all of the data presented in this study were obtained from experiments conducted on mice. As a result, VA and RA reduced body weight gain and fat accumulation while improving liver damage, inflammation, glucose, and lipid metabolism induced by a high-fat diet. Moreover, VA and RA regulated the gut microbiota composition, decreasing the pro-obesity and proinflammation bacteria taxa, such as the phylum Actinobacterium and the genera Allobaculum and Bifidobacterium, and increasing those negatively associated with obesity and inflammation, such as the phylum Bacteroidetes and the genera Prevotella and Oscillospira. Additionally, the supplementation with VA and RA reversed the elevated levels of valeric, caproic, and isovaleric acids observed in the high-fat diet (HFD) group, bringing them closer to the levels observed in the Chow group. This reversal indicated that alterations in the composition and abundance of gut microbiota may contribute to the restoration of short-chain fatty acids (SCFAs) levels. Additionally, PICRUSt2 exhibited that cyanamino acid metabolism and betalain biosynthesis might be the major metabolic pathways in the HVA group compared with the HFD group, while in the HRA group, it was the phosphotransferase system. These findings suggest that VA and RA can ameliorate MetS by modulating the gut microbiota and production of SCFAs.

Beneficial metabolic effects of PAHSAs depend on the gut microbiota in diet-induced obese mice

Dietary lipids play an essential role in regulating the function of the gut microbiota and gastrointestinal tract, and these luminal interactions contribute to mediating host metabolism. PAHSAs are a class of lipids with anti-diabetic and anti-inflammatory properties, but whether the gut microbiota contributes to their beneficial effects on host metabolism is unknown. Here, we report that treating high fat diet (HFD)-fed germ-free mice with PAHSAs does not improve insulin sensitivity. However, transfer of feces from PAHSA-treated, but not Vehicle-treated, chow-fed mice increases insulin-sensitivity in HFD-fed germ free mice. Thus, the gut microbiota is necessary for and can transmit the insulin-sensitizing effects of PAHSAs in HFD-fed germ-free mice. Functional analyses of the cecal metagenome and lipidome of PAHSA-treated mice identified multiple lipid species that associate with the gut commensal Bacteroides thetaiotaomicron ( Bt ) and with insulin sensitivity resulting from PAHSA treatment. Bt supplementation in HFD-fed female mice prevented weight gain, reduced adiposity, improved glucose tolerance, fortified the colonic mucus barrier and reduced systemic inflammation versus chow-fed controls, effects that were not observed in HFD-fed male mice. Furthermore, ovariectomy partially reversed the beneficial Bt effects on host metabolism, indicating a role for sex hormones in mediating probiotic effects. Altogether, these studies highlight the fact that lipids can modulate the gut microbiota resulting in improvement in host metabolism and that PAHSA-induced changes in the microbiota result in at least some of their insulin-sensitizing effects in female mice.

Forschung für die Praxis: Ernährung und Mikrobiom bei Autoimmunkrankheiten

Die Häufigkeit von Autoimmunerkrankungen in Industrieländern hat während der letzten Jahrzehnte ständig zugenommen. Diese Erkrankungen führen zu erhöhter Sterblichkeit sowie anhaltender Beeinträchtigung der Lebensqualität der Patienten und bedeuten eine große medizinische Belastung. Die Behandlung von Autoimmunkrankheiten beruht häufig auf unspezifischer Immunsuppression, was das Risiko von Infektionskrankheiten und Krebsmanifestationen erhöht. Die Pathogenese von Autoimmunerkrankungen ist komplex und umfasst nicht nur genetische Faktoren, sondern auch Umwelteinflüsse, die als Grund für die Zunahme von Autoimmunerkrankungen angesehen werden. Zahlreiche Umweltfaktoren wie Infektionen, Rauchen, Medikamente oder Ernährung können das Auftreten von Autoimmunität entweder fördern oder verhindern. Die Mechanismen der Beeinflussung durch Umwelteinflüsse sind jedoch komplex und derzeit noch nicht eindeutig geklärt. Die Entschlüsselung dieser Wechselwirkungen könnte unser Verständnis der Autoimmunität verbessern und neue Behandlungsmöglichkeiten für die Patienten eröffnen.

Research in practice: Diet and microbiome in autoimmune diseases

The incidence of autoimmune diseases in industrialized countries is constantly increasing over past decades. These diseases lead to increased mortality and persistent reduction in quality of life of the patients, posing a severe medical burden. Treatment of autoimmune diseases is often based on unspecific immune suppression, increasing the risk of infectious diseases as well as cancer manifestation. Pathogenesis of autoimmune conditions is complex and includes not only genetic factors, but also environmental influence, which is considered to be the reason for the rise of incidence of autoimmune diseases. Environmental factors comprise numerous elements, such as infections, smoking, medication, diet etc., which can either promote or prevent the onset of autoimmunity. However, the mechanisms of environmental influence are complex and for this moment not clearly understood. Deciphering of these interactions could enhance our comprehension of autoimmunity and provide some novel treatment options for the patients.

Mechanisms of bariatric surgery for weight loss and diabetes remission

Obesity and type 2 diabetes(T2D) lead to defects in intestinal hormones secretion, abnormalities in the composition of bile acids (BAs), increased systemic and adipose tissue inflammation, defects of branched-chain amino acids (BCAAs) catabolism, and dysbiosis of gut microbiota. Bariatric surgery (BS) has been shown to be highly effective in the treatment of obesity and T2D, which allows us to view BS not simply as weight-loss surgery but as a means of alleviating obesity and its comorbidities, especially T2D. In recent years, accumulating studies have focused on the mechanisms of BS to find out which metabolic parameters are affected by BS through which pathways, such as which hormones and inflammatory processes are altered. The literatures are saturated with the role of intestinal hormones and the gut-brain axis formed by their interaction with neural networks in the remission of obesity and T2D following BS. In addition, BAs, gut microbiota and other factors are also involved in these benefits after BS. The interaction of these factors makes the mechanisms of metabolic improvement induced by BS more complicated. To date, we do not fully understand the exact mechanisms of the metabolic alterations induced by BS and its impact on the disease process of T2D itself. This review summarizes the changes of intestinal hormones, BAs, BCAAs, gut microbiota, signaling proteins, growth differentiation factor 15, exosomes, adipose tissue, brain function, and food preferences after BS, so as to fully understand the actual working mechanisms of BS and provide nonsurgical therapeutic strategies for obesity and T2D.

The Intestinal Microbiome and the Metabolic Syndrome-How Its Manipulation May Affect Metabolic-Associated Fatty Liver Disease (MAFLD)

Metabolic-associated fatty liver disease (MAFLD) is now the predominant liver disease worldwide consequent to the epidemic of obesity. The intestinal microbiome (IM), consisting of the bacteria, fungi, archaea, and viruses residing in the gastrointestinal tract, plays an important role in human metabolism and preserving the epithelial barrier function. Disturbances in the IM have been shown to influence the development and progression of MAFLD and play a role in the development of metabolic syndrome (MS). The main treatment for MAFLD involves lifestyle changes, which also influence the IM. Manipulation of the IM by fecal microbial transplantation (FMT) has been approved for the treatment of recurrent Closteroides difficile infection. This may be administered by endoscopic administration from the lower or upper GI tract. Other methods of administration include nasogastric tube, enema, and oral capsules of stool from healthy donors. In this narrative review, we elaborate on the role of the IM in developing MS and MAFLD and on the current experience with IM modulation by FMT on MAFLD.

The Crosstalk between Gut Microbiota and Bile Acids Promotes the Development of Non-Alcoholic Fatty Liver Disease

Recently the roles of gut microbiota are highly regarded in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). The intestinal bacteria regulate the metabolism of bile acids depending on bile salt hydrolase (BSH), 7-dehydroxylation, hydroxysteroid dehydrogenase (HSDH), or amide conjugation reaction, thus exerting effects on NAFLD development through bile acid receptors such as farnesoid X receptor (FXR), Takeda G-protein-coupled bile acid protein 5 (TGR5), and vitamin D receptor (VDR), which modulate nutrient metabolism and insulin sensitivity via interacting with downstream molecules. Reversely, the composition of gut microbiota is also affected by the level of bile acids in turn. We summarize the mutual regulation between the specific bacteria and bile acids in NAFLD and the latest clinical research based on microbiota and bile acids, which facilitate the development of novel treatment modalities in NAFLD.

Effects of fecal microbiota transplantation in metabolic syndrome: A meta-analysis of randomized controlled trials

OBJECTIVE

The prevalence of obesity and type 2 diabetes is rapidly increasing worldwide, posing serious threats to human health. This study aimed to evaluate the role of FMT in the treatment of obesity and/or metabolic syndrome and its impact on clinically important parameters.

METHODS

We searched Medline, Embase, and Cochrane Library databases up to April 31, 2022 and further assessed articles that met the eligibility criteria. Mean differences and 95% confidence intervals were used to analyze continuous data. The I2 statistic was used to measure study heterogeneity. Univariate meta-regression or subgroup analyses were performed to explore the covariates that might contribute to heterogeneity. Potential publication bias was assessed using the Egger's test. We used the GRADEpro guideline development tool to assess the quality of the evidence.

RESULTS

Nine studies, comprising 303 participants, were included in the meta-analysis. In the short-term outcomes (<6 weeks after FMT), compared with the placebo group, patients in the FMT group had lower FBG (MD = -0.12 mmol/L, 95% Cl: -0.23, -0.01), HbA1c (MD = -0.37 mmol/mol, 95%Cl: -0.73, -0.01), and insulin levels (MD = -24.77 mmol/L, 95% Cl: -37.60, -11.94), and higher HDL cholesterol levels (MD = 0.07 mmol/L, 95% Cl: 0.02, 0.11).

CONCLUSIONS

FMT, as an adjunctive therapy, does not produce any serious adverse effects and may be useful in the treatment of metabolic syndrome, especially in improving HbA1c, insulin sensitivity, and HDL cholesterol. However, there was no significant difference between the FMT group and the placebo group in terms of weight reduction.

Fecal microbiota transplantation in patients with metabolic syndrome and obesity: A randomized controlled trial

BACKGROUND

Metabolic syndrome is a multifactorial disease, and the gut microbiota may play a role in its pathogenesis. Obesity, especially abdominal obesity, is associated with insulin resistance, often increasing the risk of type two diabetes mellitus, vascular endothelial dysfunction, an abnormal lipid profile, hypertension, and vascular inflammation, all of which promote the development of atherosclerotic cardiovascular disease.

AIM

To evaluate the outcomes of fecal microbiota transplantation (FMT) in patients with metabolic syndrome.

METHODS

This was a randomized, single-blind placebo-controlled trial comparing FMT and a sham procedure in patients with metabolic syndrome. We selected 32 female patients, who were divided into eight groups of four patients each. All of the patients were submitted to upper gastrointestinal endoscopy. In each group, two patients were randomly allocated to undergo FMT, and the other two patients received saline infusion. The patients were followed for one year after the procedures, during which time anthropometric, bioimpedance, and biochemical data were collected. The patients also had periodic consultations with a nutritionist and an endocrinologist. The primary end point was a change in the gut microbiota.

RESULTS

There was evidence of a postprocedural change in microbiota composition in the patients who underwent FMT in relation to that observed in those who underwent the sham procedure. However, we found no difference between the two groups in terms of the clinical parameters evaluated.

CONCLUSION

There were no significant differences in biochemical or anthropometric parameters, between the two groups evaluated. Nevertheless, there were significant postprocedural differences in the microbiota composition between the placebo group. To date, clinical outcomes related to FMT remain uncertain.

Fecal Microbiota Transplantation for Weight and Glycemic Control of Obesity as Well as the Associated Metabolic Diseases: Meta-Analysis and Comprehensive Assessment

Objectives: An analysis of the weight and blood glucose management associated with fecal microbiota transplantation (FMT) as well as metabolic diseases associated with FMT was conducted by the authors in order to provide clinical recommendations regarding the treatment of nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM). Methods: We searched PubMed, Embase, and the Cochrane Library for papers that were published between the creation of the database and October 2022. We reviewed research that investigated how FMT affected weight and glycemic management in cases of obesity and metabolic conditions that are related to obesity. Studies that were published more than once, lacked the entire text, included insufficient information, or were impossible to extract data from were excluded. Additionally, case reports, reviews, and systematic reviews were excluded from the analysis. In order to analyze the data, STATA 15.1 was used. Outcomes: When we combined all of our findings, we discovered that pooled outcomes showed that weight levels (WMD equals -4.77, 95%CI: -7.40~-2.14), BMI levels (WMD equals -1.59, 95%CI: -2.21~-0.97), HOMA-IR (WMD equals -0.79, 95%CI: -1.57~-0.00), and HbA1c (WMD equals -0.65, 95%CI: -0.75~-0.55) after FMT treatment were significantly lower than before treatment. However, FMT treatment may have no effect on glucose and insulin levels in obese patients at fasting and related metabolic diseases. Additionally, subgroup analysis outcomes found that FMT significantly reduced fasting blood glucose in people with diabetes. Conclusions: As a weight loss and glycemic control therapy, FMT helps to prevent and treat metabolic problems linked to obesity, and is a viable alternative to bariatric surgery for patients who do not wish to undergo the procedure.

Fecal microbiota transplantation in obesity metabolism: a META analysis and systematic review

OBJECTIVE

The effect of fecal microbiota transplantation (FMT) on microbiota engraftment in patients with metabolic syndrome remains unclear. This systematic review employed a meta-analysis of RCTs for assessment on the role of FMT in treating obesity and metabolic syndrome, and its impact on clinically relevant parameters.

METHOD

Major databases and grey literatures were searched identifying RCTs comparing FMT of lean donors with placebo in obese/metabolic syndrome patients. Studies using any form of placebo were included. Variations in the parameters before and after treatment were calculated followed by meta-analyses.

RESULT

Ten studies met the inclusion criteria and a total of 334 patients were included for further analysis. Clinically significant parameters associated with obesity and metabolic syndrome were explored and FMT was identified significantly and negatively associated with most indices of abdominal adiposity including caloric intake, fasting glucose, HOMA-IR, systolic blood pressure, diastolic blood pressure, total cholesterol, HDL, LDL, triglycerides and CRP, Obesity parameters including fasting glucose and acetic acid were increased following FMT.

CONCLUSION

FMT is more advantageous for obese patients with elevated blood pressure, disordered glucose and insulin metabolism, and elevated blood lipids. The study of metabolic factors in obese patients will be our starting point in the future.

Gut microbiota and obesity: an overview of microbiota to microbial-based therapies

The increasing prevalence of obesity and overweight is a significant public concern throughout the world. Obesity is a complex disorder involving an excessive amount of body fat. It is not just a cosmetic concern. It is a medical challenge that increases the risk of other diseases and health circumstances, such as diabetes, heart disease, high blood pressure and certain cancers. Environmental and genetic factors are involved in obesity as a significant metabolic disorder along with diabetes. Gut microbiota (GM) has a high potential for energy harvesting from the diet. In the current review, we aim to consider the role of GM, gut dysbiosis and significant therapies to treat obesity. Dietary modifications, probiotics, prebiotics, synbiotics compounds, using faecal microbiota transplant, and other microbial-based therapies are the strategies to intervene in obesity reducing improvement. Each of these factors serves through various mechanisms including a variety of receptors and compounds to control body weight. Trial and animal investigations have indicated that GM can affect both sides of the energy-balancing equation; first, as an influencing factor for energy utilisation from the diet and also as an influencing factor that regulates the host genes and energy storage and expenditure. All the investigated articles declare the clear and inevitable role of GM in obesity. Overall, obesity and obesity-relevant metabolic disorders are characterised by specific modifications in the human microbiota's composition and functions. The emerging therapeutic methods display positive and promising effects; however, further research must be done to update and complete existing knowledge.

Emerging applications of phage therapy and fecal virome transplantation for treatment of Clostridioides difficile infection: challenges and perspectives

Clostridioides difficile, which causes life-threatening diarrheal disease, is considered an urgent threat to healthcare setting worldwide. The current standards of care solely rely on conventional antibiotic treatment, however, there is a risk of promoting recurrent C. difficile infection (rCDI) because of the emergence of antibiotic-resistant strains. Globally, the alarming spread of antibiotic-resistant strains of C. difficile has resulted in a quest for alternative therapeutics. The use of fecal microbiota transplantation (FMT), which involves direct infusion of fecal suspension from a healthy donor into a diseased recipient, has been approved as a highly efficient therapeutic option for patients with rCDI. Bacteriophages or phages are a group of viruses that can infect and destroy bacterial hosts, and are recognized as the dominant viral component of the human gut microbiome. Accumulating data has demonstrated that phages play a vital role in microbial balance of the human gut microbiome. Recently, phage therapy and fecal virome transplantation (FVT) have been introduced as promising alternatives for the treatment of C. difficile -related infections, in particular drug-resistant CDI. Herein, we review the latest updates on C. difficile- specific phages, and phage-mediated treatments, and highlight the current and future prospects of phage therapy in the management of CDI.

Trust the gut: outcomes of gut microbiota transplant in metabolic and cognitive disorders

Type 2 diabetes mellitus (T2DM) is a main public health concern, with increasing prevalence and growingly premature onset in children, in spite of emerging and successful therapeutic options. T2DM promotes brain aging, and younger age at onset is associated with a higher risk of subsequent dementia. Preventive strategies should address predisposing conditions, like obesity and metabolic syndrome, and be started from very early and even prenatal life. Gut microbiota is an emerging target in obesity, diabetes and neurocognitive diseases, which could be safely modulated since pregnancy and infancy. Many correlative studies have supported its involvement in disease pathophysiology. Faecal material transplantation (FMT) studies have been conducted in clinical and preclinical settings to deliver cause-effect proof and mechanistic insights. This review provides a comprehensive overview of studies in which FMT was used to cure or cause obesity, metabolic syndrome, T2DM, cognitive decline and Alzheimer's disease, including the evidence available in early life. Findings were analysed to dissect consolidated from controversial results, highlighting gaps and possible future directions.

Metabolic-Associated Fatty Liver Disease and the Gut Microbiota

As an important sequela of the burgeoning global obesity problem, metabolic-associated fatty liver disease (MAFLD) has gained increasing prominence recently. The gut-liver axis (GLA) provides a direct conduit to the liver for the gut microbiota and their metabolic by-products (including secondary bile acids, ethanol, and trimethylamine). These GLA-related factors, including the host inflammatory response and integrity of the gut mucosal wall, likely contribute to the pathogenesis of MAFLD. Accordingly, these GLA-related factors are targets for possible preventive and treatment strategies for MAFLD, and include probiotics, prebiotics, bile acids, short-chain fatty acids, fecal microbiota transplantation, carbon nanoparticles, and bacteriophages.

Gut-Microbiota Dysbiosis in Stroke-Prone Spontaneously Hypertensive Rats with Diet-Induced Steatohepatitis

Metabolic-dysfunction-associated fatty-liver disease (MAFLD) is the principal worldwide cause of liver disease. Individuals with nonalcoholic steatohepatitis (NASH) have a higher prevalence of small-intestinal bacterial overgrowth (SIBO). We examined gut-microbiota isolated from 12-week-old stroke-prone spontaneously hypertensive-5 rats (SHRSP5) fed on a normal diet (ND) or a high-fat- and high-cholesterol-containing diet (HFCD) and clarified the differences between their gut-microbiota. We observed that the Firmicute/Bacteroidetes (F/B) ratio in both the small intestines and the feces of the SHRSP5 rats fed HFCD increased compared to that of the SHRSP5 rats fed ND. Notably, the quantities of the 16S rRNA genes in small intestines of the SHRSP5 rats fed HFCD were significantly lower than those of the SHRSP5 rats fed ND. As in SIBO syndrome, the SHRSP5 rats fed HFCD presented with diarrhea and body-weight loss with abnormal types of bacteria in the small intestine, although the number of bacteria in the small intestine did not increase. The microbiota of the feces in the SHRSP5 rats fed HFCD was different from those in the SHRP5 rats fed ND. In conclusion, there is an association between MAFLD and gut-microbiota alteration. Gut-microbiota alteration may be a therapeutic target for MAFLD.

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

Gut Microbiome and Its Impact on Obesity and Obesity-Related Disorders

PURPOSE OF REVIEW

The prevalence of overweight and obesity has been increasing worldwide at an alarming rate. Gut microbiota intimately influence host energy metabolism, and immune response. Studies indicate a prominent role of gut dysbiosis in propagating inflammation that is associated with the development of obesity and obesity-related disorders such as type 2 diabetes mellitus, metabolic syndrome, and non-alcoholic fatty liver disease. This article will review the current literature on gut microbiome and its impact on obesity and obesity-related disorders.

RECENT FINDINGS

An altered gut microbial composition in obesity and obesity-related disorders is associated with enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability, increased production of proinflammatory metabolites, such as lipopolysaccharides, resulting in systemic inflammation and insulin resistance. Gut microbiota modulation can be achieved either by dietary manipulation or by administration of probiotics, prebiotics, synbiotics, and/or fecal microbiota transplantation aiming at the improvement of the gut dysbiosis in obesity and metabolic disorders. Further clinical trials are required to better elucidate the dose, and frequency of these interventions and also their long-term impact on host metabolism.

Effect of faecal microbial transplant via colonoscopy in patients with severe obesity and insulin resistance: A randomized double-blind, placebo-controlled Phase 2 trial

AIM

To assess the effects of faecal microbial transplant (FMT) from lean people to subjects with obesity via colonoscopy.

MATERIAL AND METHODS

In a double-blind, randomized controlled trial, subjects with a body mass index ≥ 35 kg/m² and insulin resistance were randomized, in a 1:1 ratio in blocks of four, to either allogenic (from healthy lean donor; n = 15) or autologous FMT (their own stool; n = 13) delivered in the caecum and were followed for 3 months. The main outcome was homeostatic model assessment of insulin resistance (HOMA-IR) and secondary outcomes were glycated haemoglobin levels, lipid profile, weight, gut hormones, endotoxin, appetite measures, intestinal microbiome (IM), metagenome, serum/faecal metabolites, quality of life, anxiety and depression scores.

RESULTS

In the allogenic versus autologous groups, HOMA-IR and clinical variables did not change significantly, but IM and metabolites changed favourably (P < 0.05): at 1 month, Coprococcus, Bifidobacterium, Bacteroides and Roseburia increased, and Streptococcus decreased; at 3 months, Bacteroides and Blautia increased. Several species also changed significantly. For metabolites, at 1 month, serum kynurenine decreased and faecal indole acetic acid and butenylcarnitine increased, while at 3 months, serum isoleucine, leucine, decenoylcarnitine and faecal phenylacetic acid decreased. Metagenomic pathway representations and network analyses assessing relationships with clinical variables, metabolites and IM were significantly enhanced in the allogenic versus autologous groups. LDL and appetite measures improved in the allogenic (P < 0.05) but not in the autologous group.

CONCLUSIONS

Overall, in those with obeisty, allogenic FMT via colonoscopy induced favourable changes in IM, metabolites, pathway representations and networks even though other metabolic variables did not change. LDL and appetite variables may also benefit.

Liver-Gut-Interaction: Role of Microbiome Transplantation in the Future Treatment of Metabolic Disease

The association between shifts in gut microbiome composition and metabolic disorders is a well-recognized phenomenon. Clinical studies and experimental data suggest a causal relationship, making the gut microbiome an attractive therapeutic goal. Fecal microbiome transplantation (FMT) is a method to alter a person's microbiome composition. Although this method allowed for the establishment of proof of concept for using microbiome modulation to treat metabolic disorders, the method is not yet ready for broad application. It is a resource-intensive method that also carries some procedural risks and whose effects are not always reproducible. This review summarizes the current knowledge on FMT to treat metabolic diseases and gives an outlook on open research questions. Further research is undoubtedly required to find applications that are less resource-intensive, such as oral encapsulated formulations, and have strong and predictable results. Furthermore, a clear commitment from all stakeholders is necessary to move forward in the direction of developing live microbial agents, next-generation probiotics, and targeted dietary interventions.

The Black Box Orchestra of Gut Bacteria and Bile Acids: Who Is the Conductor?

Over the past decades the potential role of the gut microbiome and bile acids in type 2 diabetes mellitus (T2DM) has been revealed, with a special reference to low bacterial alpha diversity. Certain bile acid effects on gut bacteria concern cytotoxicity, or in the case of the microbiome, bacteriotoxicity. Reciprocally, the gut microbiome plays a key role in regulating the bile acid pool by influencing the conversion and (de)conjugation of primary bile acids into secondary bile acids. Three main groups of bacterial enzymes responsible for the conversion of bile acids are bile salt hydrolases (BSHs), hydroxysteroid dehydrogenases (HSDHs) and enzymes encoded in the bile acid inducible (Bai) operon genes. Interventions such as probiotics, antibiotics and fecal microbiome transplantation can impact bile acids levels. Further evidence of the reciprocal interaction between gut microbiota and bile acids comes from a multitude of nutritional interventions including macronutrients, fibers, prebiotics, specific individual products or diets. Finally, anatomical changes after bariatric surgery are important because of their metabolic effects. The heterogeneity of studies, diseases, bacterial species and (epi)genetic influences such as nutrition may challenge establishing specific and detailed interventions that aim to tackle the gut microbiome and bile acids.

Protective Effect of Vegan Microbiota on Liver Steatosis Is Conveyed by Dietary Fiber: Implications for Fecal Microbiota Transfer Therapy

Fecal microbiota transfer may serve as a therapeutic tool for treating obesity and related disorders but currently, there is no consensus regarding the optimal donor characteristics. We studied how microbiota from vegan donors, who exhibit a low incidence of non-communicable diseases, impact on metabolic effects of an obesogenic diet and the potential role of dietary inulin in mediating these effects. Ex-germ-free animals were colonized with human vegan microbiota and fed a standard or Western-type diet (WD) with or without inulin supplementation. Despite the colonization with vegan microbiota, WD induced excessive weight gain, impaired glucose metabolism, insulin resistance, and liver steatosis. However, supplementation with inulin reversed steatosis and improved glucose homeostasis. In contrast, inulin did not affect WD-induced metabolic changes in non-humanized conventional mice. In vegan microbiota-colonized mice, inulin supplementation resulted in a significant change in gut microbiota composition and its metabolic performance, inducing the shift from proteolytic towards saccharolytic fermentation (decrease of sulfur-containing compounds, increase of SCFA). We found that (i) vegan microbiota alone does not protect against adverse effects of WD; and (ii) supplementation with inulin reversed steatosis and normalized glucose metabolism. This phenomenon is associated with the shift in microbiota composition and accentuation of saccharolytic fermentation at the expense of proteolytic fermentation.

The 7-α-dehydroxylation pathway: An integral component of gut bacterial bile acid metabolism and potential therapeutic target

The gut microbiome plays a significant role in maintaining host metabolic health through the production of metabolites. Comprising one of the most abundant and diverse forms of gut metabolites, bile acids play a key role in blood glucose regulation, insulin sensitivity, obesity, and energy expenditure. A central pathway in gut bacterial bile acid metabolism is the production of secondary bile acids via 7-ɑ-dehydroxylation. Despite the important role of 7-ɑ-dehydroxylation in gut bacterial bile acid metabolism and the pathophysiology of metabolic disease, the regulation of this pathway is not completely understood. This review aims to outline our current understanding of 7-ɑ-dehydroxylation and to identify key knowledge gaps that will be integral in further characterizing gut bacterial bile acid metabolism as a potential therapeutic target for treating metabolic dysregulation.

Treatment of Dyslipidemia through Targeted Therapy of Gut Microbiota

Dyslipidemia is a multifaceted condition with various genetic and environmental factors contributing to its pathogenesis. Further, this condition represents an important risk factor for its related sequalae including cardiovascular diseases (CVD) such as coronary artery disease (CAD) and stroke. Emerging evidence has shown that gut microbiota and their metabolites can worsen or protect against the development of dyslipidemia. Although there are currently numerous treatment modalities available including lifestyle modification and pharmacologic interventions, there has been promising research on dyslipidemia that involves the benefits of modulating gut microbiota in treating alterations in lipid metabolism. In this review, we examine the relationship between gut microbiota and dyslipidemia, the impact of gut microbiota metabolites on the development of dyslipidemia, and the current research on dietary interventions, prebiotics, probiotics, synbiotics and microbiota transplant as therapeutic modalities in prevention of cardiovascular disease. Overall, understanding the mechanisms by which gut microbiota and their metabolites affect dyslipidemia progression will help develop more precise therapeutic targets to optimize lipid metabolism.